Method and apparatus for making a tablet of powdered products for espresso beverage extraction

ABSTRACT

A method of making a tablet for hot espresso beverage extraction includes the steps of grinding a brewable product to obtain a powder having a substantially uniform particle size, dosing a predetermined amount of the ground product powder, moistening the powdered product dose, homogenizing the moistened mixture to obtain a powdered product with a substantially uniform moisture content, forming the powdered product dose to obtain a disk-shaped or prismatic tablet, and supplying an amount of energy to the tablet to obtain a substantially compact and integral item. The step of supplying energy is carried out by irradiating the tablet with an electromagnetic wave beam to overheat and partially bake and/or sinter the particles of the powdered product and impart a relatively compact and self-supporting construction to the finished tablet. The electromagnetic wave irradiation step is carried out at the end of the forming step while continuously compressing the dose.

FIELD OF THE INVENTION

The present invention generally finds application in the food industryand particularly relates to a method and arrangement for making a tabletof powdered products for espresso beverage extraction.

BACKGROUND OF THE INVENTION

Certain espresso beverages are known to be obtained by brewing orinstantaneous extraction of flavors and active ingredients of more orless edible products, such as coffee, barley, malt, ginseng, infusionsand other similar products in powder or particle form, using warm or hotwater at ambient pressure or preferably at a pressure above theatmospheric pressure.

As used herein, the term espresso is intended to designate a beveragethat is prepared instantaneously or for a waiting consumer.

A particular class of base products requires grinding to obtain productsof various particle sizes.

A typical, non-exclusive example of such class of products is coffee,which is previously mixed, roasted and then cold-ground to obtain theclassical coffee grounds that are sold in hermetically and vacuum sealedpackages for home and public use.

In order to prepare an espresso coffee, a given amount of coffee groundsis loaded in a perforated container, known as filter container,whereupon the loaded grounds are compressed manually or using a specialtamper.

Then, hot water is forced through the compressed grounds are at a givenpressure, using a special machine.

A high-quality espresso coffee, as typically requested in bars, requiressome skill and a high-cost professional machine.

For domestic preparation of high-quality espresso coffee, portions ofcoffee grounds have been long available, which are pre-packaged as podsmade of filter paper or plastic capsules of various shapes and sizes.These items are introduced into relatively inexpensive machines, whichare affordable to private consumers or small-size businesses andcommunities, to prepare a top-quality espresso.

Examples of these pre-packaged items are disclosed, for instance, in FR1 029 940, U.S. Pat. No. 1,951,357, U.S. Pat. No. 4,394,395, IT 1 213385.

One drawback of such prior art methods and items for preparing espressocoffee consists in the relatively high costs for manufacturing andpackaging capsules or pods, which results in accordingly high salescosts for the final consumer.

A further drawback is that this known type of packaging requires thepresence of enclosures made of plastic, paper, aluminum or othermaterials to contain the products to be filtered, which make themanufacturing process more complex and problematic.

Yet another drawback relates to environment-friendly disposal andenvironmental impact reduction issues, due to such enclosures, aftercoffee dispensing.

In an attempt to obviate the above drawbacks, a novel process has beendeveloped for producing tablets or pastilles that does not require anykind of enclosure, but requires moistening of the tablet and applicationof energy thereto, in the form of vibrations, namely high-frequencyultrasonic vibrations.

Processes of this type are disclosed and claimed, for instance, inEP1956921 e WO2001/027426.

While this novel preparation method has provided a number of advantagesover prior art products, such as the elimination of the plasticenclosure for coffee grounds, which considerably reduces environmentalimpact, it still has the drawback that vibrations are required to betransferred by contact or through an interposed medium, which increasesthe complexity and costs of the manufacturing process.

Furthermore, the tablet is not uniformly compacted, as ultrasonic wavesare progressively attenuated as they pass through the tablet, and thetablet cannot be compacted above a given thickness limit.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the above drawbacks,by providing a method of producing a tablet of ground powdered productsfor hot espresso beverage extraction that is highly efficient andrelatively cost-effective.

A particular object of the present invention is to provide a method asdescribed above which avoids the use of enclosures for tablets ofbrewable products.

A further object is to conceive a method as described above whichaffords a considerable reduction of manufacturing process and equipmentcosts.

Yet another object is to provide a tablet for espresso beveragepreparation that has a substantially integral self-supportingconstruction.

These and other objects, as more clearly shown hereinafter, arefulfilled, as defined in claim 1, by a method of making a tablet for hotespresso beverage extraction, comprising the steps of grinding abrewable product to obtain a powder having a substantially uniformparticle size, dosing a predetermined amount of said ground productpowder, moistening the powdered product dose, forming the dose ofmoistened powdered product by compression to obtain a substantiallydisk-shaped tablet, supplying an amount of energy to said tablet toobtain a substantially compact and integral item.

The method is characterized in that the step of supplying energy iscarried out at a distance by irradiating the tablet with anelectromagnetic wave beam to overheat and partially bake and/or sinterthe particles of the powdered product as well as to impart a relativelycompact and self-supporting construction to the tablet.

In a second aspect, the invention relates to an arrangement for making atablet of ground powdered products for hot espresso beverage extractionas defined in claim 13, which comprises forming means having a hollowbody for collecting a powdered product dose, compression means forcompressing the product dose collected in said hollow body and forming atablet having a desired shape, means for supplying energy to the tabletformed within said hollow body.

In a further aspect, the means for supplying energy comprise irradiatingmeans for remote emission of an electromagnetic wave beam directedtoward said hollow body, to overheat and partially bake and/or sinterthe particles of the powdered products of the tablet as well as toimpart thereto a relatively compact and self-supporting constructionwithout requiring any outer enclosure.

Particular embodiments of the method and arrangement of the inventionare described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will be moreapparent upon reading of the detailed description of a few preferred,non-exclusive embodiments of a method and apparatus for producing atablet for hot espresso beverage extraction, which are described asnon-limiting examples with the help of the annexed drawings, in which:

FIG. 1 is a block diagram of the inventive method;

FIG. 2 is a schematic view of a first embodiment of an apparatus forcarrying out certain steps of the method of FIG. 1;

FIG. 3 is a schematic view of a variant embodiment of the apparatus ofFIG. 2.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Particularly referring to the above mentioned figures, the method forproducing a tablet for hot espresso beverage extraction may beadvantageously used for brewable products of various types, as long asthey can be actually brewed, including without limitation coffee,barley, malt, ginseng, tea, hibiscus tea, infusions and other similarproducts in powder or particle form.

While the method is described below with reference to a coffee tablet,it is applicable to any of the above mentioned products.

As briefly shown in the block diagram of FIG. 1 the method comprises aprevious preparation of a blend of coffee grains, after conventionalroasting.

Then, the coffee blend undergoes a grinding step a) to obtain groundshaving a substantially uniform particle size, herein referred to as“powered product” substantially in the dry state or with very lowresidual moisture content.

The powdered product will undergo a dosing step b) by special volumetricdosing or weighing units, such that a dose of a predetermined amount ofproduct is isolated.

The product dose will undergo a moistening step c) with 2% to 20%,preferably about 10% liquid, preferably untreated water, based on theweight of dry powdered product.

Possibly, appropriate binders may be used for improving mutual adhesionof the powder particles in the later steps.

The powdered product, after addition of water and other binders, if any,will preferably undergo a homogenization step d), e.g. by stirring witha special spindle or vibration mixer, or with any other means that canprovide a substantially uniform moistened mixture.

Now, the moistened and homogenized mixture undergoes a forming step e)to assume a predetermined shape.

Particularly, the forming step e) may be carried out by an apparatus asdescribed below, which is adapted to compress the moistened mixture intoan item, e.g. a disk-shaped or prismatic item, hereinafter referred toas tablet C or pastille.

Preferably, the pressure applied to the powdered product ranges from 1bar to 5 bar, and is preferably about 2.5 bar. Conveniently, compressionwill be carried out by pneumatic, hydraulic or technically equivalentmeans.

The tablet C so formed shall be anyway adapted to be introduced into ahot water or steam coffee machine of a known type and also suitable foruse in home environments.

A key step of the step is the supply d) of a given amount Q of energy,which causes heating of the previously formed tablet C, to impart asubstantially compact and integral construction thereto.

A peculiar feature of the invention is that the step f) of supplyingsaid energy is carried out by irradiating the tablet C with anelectromagnetic wave beam.

Conveniently, the irradiation step starts as soon as the forming step iscompleted, and while continuously holding the tablet under pressurethroughout the irradiation step, to stabilize the shape and structure ofthe tablet C.

Electromagnetic waves are known to be a form of energy that istransferred through space without requiring any interface of contactmedium, whereby this step may be carried out at a distance, by simplydirecting the beam toward the tablet.

Tests and analyses showed that the best results are obtained byselecting an electromagnetic wave frequency in the microwave range.

Particularly the frequency of microwaves may advantageously range from0.915 to 5.8 GHz, and preferably be about 2.45 GHz.

Microwave irradiation is conducted in a substantially constant fashion,for a predetermined time T, ranging from a few seconds to 2 minutes, andpreferably less than 60 seconds.

Preferably, the electromagnetic beam has a specific power P ranging from30 to 500 W per gram of powdered product, preferably of about 150 W pergram of powdered product.

It will be appreciated that the powdered product that forms the tablet Ccontains a given amount of water, whose molecules behave like electricdipoles having a given dipole moment.

Since the wavelength of microwaves is of the same order of magnitude asthat of water dipoles, microwaves will cause an increase of therotational energy of such dipoles in the mass of the tablet C, therebyalmost instantaneously heating water and the surrounding product.

Since water molecules are substantially evenly distributed in the massof the tablet, the base material of the tablet will undergosubstantially uniform and “core” heating, without creating zones withdifferentiated hardness.

Therefore, the compressed and microwave-irradiated granular product willbe somewhat “baked” and/or “sintered” in a very short time, typically afew seconds, thereby creating a self-supporting and integral structure,which is considerably porous and extractable, in the tablet.

The need is thus avoided for any outer enclosure, which would also havesome barrier effect, and may limit flavor extraction from the product.

At the end of the energy supply step f), a short rest step h) may beenvisaged for the tablet C, followed by a step in which the latterundergoes individual or multiple packaging i).

An arrangement that may be used for carrying out the above mentionedprocess comprises, in sequence, volumetric dosing or weighing units forisolating a dose of a predetermined amount of product, a specialspindle, vibration mixer or any other homogenizing means for stirringthe powdered product and providing a substantially uniform moistenedmixture and an apparatus that may be used for carrying out the formingstep e) and the electromagnetic irradiation step g).

FIG. 2 shows a first embodiment of an apparatus which is generallydesignated with numeral 1 and comprises a forming device 2 and anirradiation device 3.

The forming device 2 comprises a substantially tubular body 4 with asubstantially cylindrical inner cavity 5, closed at its bottom and witha top opening designed to be closed by a cover 6 that may be removablylocked by screw fastener means 7.

Both the inner cavity 5 and the closure means 6, 7 may have aconfiguration other than that described above, without departing fromthe scope of the invention.

A piston 8 is sealingly and slidably housed in the cavity 5 and may bepushed upwards by compressed air or an equivalent pressurized fluidintroduced into the cavity through a lateral air duct 9.

An air exhaust valve 10 is provided in the lower portion of the tubularbody 4, to remove compressed air after compression.

A compression chamber 11 is created between the top face of the piston 8and the bottom face of the cover 6, for receiving the powdered productdose which is later compressed.

Possibly, air bleeder means, not shown, may be provided in thecompression chamber, to avoid backpressures in the chamber 11 as thepiston 8 rises.

The irradiation device 3 may comprise a bell-shaped shield 12 holdingtherein a generator 13 of electromagnetic, particularly microwave waves,e.g. a magnetron as typically used in home microwave ovens.

The generator 13 is equipped with an antenna 14 and deflection mirrorsor waveguides 15, which have the purpose of directing the beam F towardthe target, i.e. the forming device 2, from a distance and incontactless fashion.

As is known per se, the generator 13 receives power from a power sourceconnected to its terminals 16 via a cable and a switch, not shown.

In operation, once the powdered product dose has been poured into thecompression chamber 11, the cover 6 has been secured by the screwfastener means 7 and the valve 10 has been closed, air at an appropriatepressure is introduced, to push the piston 8 upwards, compress thepowdered product dose and form the tablet C.

Immediately after complete formation of the tablet C, i.e. when thepiston 8 has reached its uppermost position and has compressed thepowdered product dose, the generator 13 is powered and emits the beam Fto irradiate the tablet C.

Of course, for loss- or spark-free irradiation, the forming device 2shall be entirely formed with microwave transparent materials.

FIG. 3 shows an alternative embodiment of the apparatus of FIG. 2,referenced 101, which basically comprises a forming device 102 and anelectromagnetic wave beam irradiating device 103.

Here again the forming device 102 may essentially consist of a hollowbody 104 with an inner cavity 105 or a forming die adapted to receive aunit powdered product dose. For this purpose, the inner cavity 105 has asubstantially cylindrical shape, or anyway a shape substantiallyconforming that of the tablet C to be formed.

The hollow body 104 also has an upper flange and is closed by aremovable cover 106 having an upper opening for the passage of the stem107 of a piston 108. The stem 107 is connected at its top to an actuator109, e.g. consisting of a pneumatic or hydraulic cylinder, which isconnected to a pressurized fluid source, not shown.

Possibly, a presser 110 may be provided in the lower portion of thehollow body 104, for ejecting the finished tablet C once heat treatmentthereon is completed.

A variable-volume compression chamber 111 is thus formed between theinner cavity 105 and the piston 108, which is designed to compress thepowdered product dose and form the tablet C.

A radiant device, generally referenced 103 is associated with theforming device 102, and comprises an electromagnetic wave beam emittingantenna 114.

The antenna 114 is at the end of a waveguide 115 having at its end aconnection 116 for a coaxial cable connected to a microwave generator,e.g. a magnetron, both not shown.

Conveniently, an annular labyrinth shield 117 may be arranged along theouter peripheral edge of the cover 106, for cooperating with the upperflange of the hollow body 102 to hold the microwaves within the radiantdevice 103.

While the above described embodiments of the apparatus are both designedto form one tablet at a time, further embodiments may be provided of anapparatus for packaging multiple tablets at a time, which would bedesigned to be introduced into a mass production line.

An exemplary process of making a tablet or pastille C is brieflydescribed below.

EXAMPLE

A typical coffee blend is used, which is instantly ground.

Then a dosed amount of 7.2 grams of coffee grounds is separated. 0.8grams of water are added, and accurately mixed for moisturehomogenization.

The dose is poured into the compression chamber 11, 111 of the formingdevice 2, 102. Compressed air at a pressure of about 2.6 bar isintroduced into the inner cavity 5 or the pneumatic cylinder of theactuator 109 to compress the powdered product and form an approximatelydisk-shaped tablet C having a diameter of 40 mm and a thickness of about9.5 mm.

Now, the microwave generator is turned on for a time T of about 10seconds, to generate a beam F having a power of about 1000 W.

The weight of the pastille after baking is about 7.6 grams, with a totalmass loss of about 0.4 grams due to partial evaporation of water and theliquid components of coffee.

The above described method and apparatus fulfill the intended objects asstated in the introduction, and particularly provide a tablet of groundpowdered products for hot espresso beverage extraction having remarkableefficiency and self-support features, without using any outer enclosureand with a considerable manufacturing cost reduction.

The method and apparatus of this invention are susceptible to a numberof changes or variants, within the inventive concept disclosed in theappended claims. All the details thereof may be replaced by othertechnically equivalent parts, and the materials may vary depending ondifferent needs, without departure from the scope of the invention asdefined in the claims.

The invention claimed is:
 1. An arrangement for making a powderedproduct tablet for hot extraction of an espresso beverage using one ormore ground brewable products, comprising: a volumetric dosing orforming unit adapted to isolate a product dose of a predetermined amountof a ground product; and an apparatus comprising: a forming unit havinga hollow body configured to receive the product dose in moistenedconditioned; a compression member associated with the hollow body andconfigured to compress the product dose collected therein and form atablet having a desired shape; and a unit supplying energy to the tabletformed within the hollow body, the unit supplying energy comprising anirradiating device that emits a microwave beam, wherein the apparatusfurther comprises a spindle, vibration mixer, or other homogenizingdevice configured to stir the ground product and provide an essentiallyuniform moistened mixture, and wherein the irradiating device comprisesa microwave generator connected to an antenna emitting anelectromagnetic wave beam directed toward the hollow body to cause anoverheating, partial baking, or sinterization of particles of the groundproduct and to partially bake or sinterize the particles and to impartthereto an essentially compact and self-supporting structure without anyouter wrapping.
 2. The arrangement as claimed in claim 1, wherein thehollow body has a substantially cylindrical inner cavity having oneclosed end and one opposite end configured to be opened for receivingthe product dose, and to be closed to define a compression chamberhaving a shape corresponding to a shape of the tablet to be formed. 3.The apparatus as claimed in claim 2, wherein said compression membercomprises a piston that is slidably and sealingly arranged within thecylindrical inner cavity and is designed to be externally driven tocompress the product dose by its longitudinal stroke.